1. Field of the Invention
The present invention relates to a sensor module that switches a plurality of sensors capable of measuring different ranges to extend a dynamic range, and particularly relates to a technique suitable for a current sensor module using a plurality of magnetic sensors capable of measuring different magnitudes of magnetic fields.
2. Description of the Related Art
As a method of extending the range of measurement of a sensor, a method of switching sensors capable of detecting different magnitudes of physical quantities is generally known. In a sensitivity switching-type sensor circuit disclosed in U.S. Pat. No. 7,382,150 B2 described below, the voltages of shunt resistors are amplified in an amplifier for a small current of a high gain and an amplifier for a large current of a low gain, respectively. After a low-frequency component is extracted by a low-pass filter, the output signals of the respective amplifiers are converted into pieces of detection data x and y which are digital values in an A/D converter, and are loaded into a microcomputer. In the microcomputer, a current value is calculated on the basis of the detection data x in a case where the detection data x of the amplifier for a small current is smaller than a threshold iL, and a current value is calculated on the basis of the data y in a case where the detection data y of the amplifier for a large current is larger than a threshold iH (>iL).